I recomend as much cardio as you can incorporate before it starts to hinder your lifting and your overall sleep, and work schedule.
For me When I diet all I have to do is 20-30 minutes a day either before lifting, after lifting or as another workout. I found out for me it does not really matter when you hit the cardio just as long as you get it in. I would try to avoid cardio on an empty stomach like most people recommend as in doing it before breakfast. Once you start to hit a defecit in your calories it really wont matter when you get your cardio in.
Avoid HIT cardio near your back and leg workouts ie stairmaster, fast paced sprinting, row machine.
Remember to mix it up accordingly. You cant just do the treadmill, your body will adapt to each session you put it through. So some sessions focus on HIT for 20 minutes. Some sessions focus on keeping a solid pace for 25-30 min. Some sessions focus on HIT interval for 15 min then slow paced for 10-15 min etc etc.
The tricky part is at first we are all really ramped up and excited to loose weight so we are able to put in 45 min here and 1hr here but how long does that motivation last? When you start dieting past your set point your body will start telling you everything possible in order to get you to break your training or diet routine. STAY STRONG when this happens. A good way to stay strong when this happens is to keep your cardio controlled and limited in the beginning that way you will have the desire and will to push when it starts to get tougher ie weeks 12-16 are the worst. By keeping it at 20-30 minutes each session you give yourself a better opportunity to staying on track with your goals as the weeks progress and your mental focus starts to fade.
So as a recommendation for you I would start with 3-4 cardio sessions a week. Then every week start to add in one more session. In the week if you start to notice your lifts start to fade from lack of mental focus, lack of pump, lack of intensity then you have hit your threshold. Decrease cardio by 2 sessions and stay there for the rest of the diet and switch focus back on lifting.
Hope this helps out.